Hydraulic control of downhole systems has long been a trusted and thus ubiquitous choice of well operators. Hydraulic control lines are relatively small, are simple to operate and very reliably transmit pressure to distant locations where either the existence of pressure is used as a signal or a higher pressure fluid volume is used to actuate a shiftable device downhole.
In older well completions relatively little control was used in the downhole environment and correspondingly few control lines were needed to extend back to the surface. In view of the relatively small number of lines, dealing with them with openings through packers (feed-through packers, etc.) and the like has always been accepted and functional. As wellbore complexity has increased however with an ever-expanding need for control related to improved production quality and quantity, a greater number of flow modifying structures (e.g. valves) and other downhole equipment has been placed downhole to enhance return on investment. With the additional devices downhole comes a requirement to provide a control regime for such devices. While hydraulic control lines are still quite well favored as a control means, the multiplicity of controllable devices causes the number of control lines required with today's technology to exceed the space available to run them. In many typical completions today the number of control lines will equal the number of devices plus 1. With consideration of the possibility of 15000 feet of wellbore having perhaps 40 valves or other controllable devices, it is easily imagined that the needed 41 control lines will have difficulty fitting in the 9⅝ inch annulus around a completion string.
In view of the foregoing, the art would certainly welcome a means for reducing the number of control lines necessary to individually control a multiplicity of devices downhole.